The present invention relates to thermoplastic molding compositions composed of the following components:    (A) at least one polyarylene ether (A1) having an average of at most 0.1 phenolic end groups per polymer chain, and at least one polyarylene ether (A2) having an average of at least 1.5 phenolic end groups per polymer chain,    (B) at least one fibrous or particulate filler, and    (C) optionally further additives and/or processing aids.
The present invention further relates to a process for producing the thermoplastic molding compositions of the invention, the use of these for producing moldings, fibers, foams, or films, and to the resultant moldings, fibers, foams, and films.
Polyarylene ethers are engineering thermoplastics, and the high heat resistance and high chemicals resistance of these materials lead to their use in very demanding applications. Polyarylene ethers are amorphous and therefore often have inadequate resistance to aggressive solvents. Polyarylene ethers also have high melt viscosity, and this is particularly disadvantageous for processing to give large moldings by means of injection molding. The high melt viscosity is particularly disadvantageous for producing molding compositions with high filler loading or high fiber loading.
Processing to give complex components often requires a marked increase in melt temperature during injection molding, to from 390 to 410° C., and in many instances this causes undesired impairment of the processing properties of the products. The property known as melt stability is used to characterize susceptibility to undesired side-reactions in the melt, where these mostly lead to molecular-weight increase and/or crosslinking. A quantitative parameter for melt stability is in particular available from the ratio of the melt volume flow rate (MVR) determined during two different residence times at a given temperature.
US 2003/0022964 A1 discloses glassfiber-reinforced thermoplastic molding compositions based on polyarylene ether sulfones. The glass fibers were pretreated with a polyolefin wax. The application does not disclose any teaching that relates to the end groups of the polyarylene ether sulfones.
WO 03/033565 A1 discloses thermoplastic molding compositions based on polyarylene ether sulfones with improved melt stability. To this end, polyarylene ether sulfones having units that derive from 1,1,1-tris(4-hydroxyphenyl)ethane are added to the molding compositions. The molding composition can optionally comprise fillers. The application does not disclose any teaching relating to the end groups of the polyarylene ether sulfones.
EP-A 855 430 discloses fiber-reinforced polyarylene ethers which comprise functionalized polyarylene ethers in order to improve toughness. Said products also exhibit improved melt stability, alongside improved toughness. The processing properties of the thermoplastic molding compositions of EP-A 855 430 are not adequate for all applications. In particular, melt stability requires further improvement. The application does not disclose any teaching relating to the end groups of the polyarylene ether sulfones.